Synergistic antioxidants



ddlidhb Patented Dec. 24, i363 This invention relates to improved organic material and in particular to the use of a synergistic combination of additives to protect organic material from deterioration.

Organic compositions including hydrocarbon fuels, lubricants and polymers are all subject to oxidative deterioration at elevated temperatures or upon prolonged exposure to the elements. In the case of lubricating compositions, gums sludges, the corrosion of metal parts with which the oils come in contact, and the loss of lubricating properties result from this deterioration. As to polymeric compositions including natural rubber and polyethylene, oxidative deterioration causes the loss of desirable characteristics as well as an increase in weight Hydrocarbon fuel compositions are deteriorated by oxygen during storage to form undesirable components in the fuel.

A principal object of this invention is to provide compositions of matter protected against oxidative deterioration. A further object is to provide synergistic compositions of additives which are highly effective in inhibiting the oxidative deterioration of hydrocarbon fuels, oils, greases, and polymeric and other organic compositions. Another object is to provide lubricating oil normally tending to deteriorate in the presence of oxygen containing, in amount sufiicien't to inhibit such deterioration, novel and highly effective antioxidant combinations. Still another object is to provide organic polymers, particularly polypropylene, stabilized against oxidative deterioration and discoloration by the presence therein of a small quantity of novel and hi hly eifective antioxidant combinations. A still further object is to provide improved antilmock fluids. Another object is to provide stabilized edible material. Other important objects of this invention will be apparent from the following description.

The above and other objects of this invention are accomplished by providing, as new compositions of matter, organic material tending to deteriorate in the presence of air, oxygen, or ozone protected by a small quantity of a mixture of a 3,S-dialltyl-4-hydroxybenzyl amine having the general formula:

wherein R is an alkyl group containing from 1 to 12 carbon atoms, R: is an alkyl group containing from 3 to 12. carbon atoms which is branched on the alpha carbon atom, R is selected from the group consisting of alkyl, cycloalkyl, aralkyl, aryl, and alkaryl and and R is selected from the group consisting of hydrogen, alkyl, cycloallcyl, aralkyl, aryl and alkaryl (in the above hydroxybenzyl amine compounds it is preferable that the hydrocarbon radicals of the groups designated above as R and R contain the following ranges of carbon atoms:

alkyl, 1 to 12; cycloalkyl, 5 to 6; aralkyl, 7 to 11; aryl, 6 to 10; and alkaryl, 7 to 15), and an organic dialkyl phosphonate having hydrogen bonded to phosphorus. In compounding the compositions of this invention, the benzyl amine is ordinarily employed in concentrations of from about 0.01 to about 5 percent based on the weight of the material to be protected while the organic hydrogen phosphonate is employed in concentrations of from about 0.005 to about 1.5 weight percent of phosphorus based on the material to be protected.

Ordinarily when employing the synergistic antioxidant mixtures of this invention it is preferable to use from 0.025 to about 0.5 weight percent of phosphorus along with from 0.2 to about 1 percent by weight of the hydroxybenzyl amine employed. These concentration ranges are preferred as synergistic antioxidant effectiveness of outstanding proportion h'as been observed in these ranges.

Typical benzyl amine compounds employed in this invention include:

N-cycrohexyl-N- 3 -methyl-5 -isopropyl-4-hydroxybenzyl) amine,

N-benZyl-N- 3 ,5 -diisopropyl-4-hydroxybenzyl amine,

N- enzyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine,

N-phenyl-N- 3 -methyl-5- (2-octyl -4-hydroxybenzyl) amine,

N- 3 ,5 -xylyl) -l-l- 3,5-di-tert-amyl-4-l1ydroxybenzyl) amine,

N-cyclohexyl-N,N-bis- 3 ,5 -diisopropyl-4-hydroxybenzyl) amine,

N- (p-butylbenzyl -N,N-bis- 3,5-di-tcrt-butyl-4-hydroxybenzyl) amine,

N-benzyl-N,N-bis-( 3 -rnethyl-5-( 1 1,3,3-tetra-methylbutyl -4-hydroxybenzyl) amine,

N- ot-naphthyl) -N,N-bis- 3,5-diisopropyl-4-hydroxybenzyl) amine,

N- (p-tolyl) -N,N-bis- 3 ,5 -di- (Z-dodecyl -4-l1ydroxybenzyl) amine,

N,N-di- (phenyl -N- 3 ,5 -di( Z-hexyl) -4-hydroxybenzyl) amine,

N-phenylN p-tolyl) -N- 3 ,5 -di- (Z-amyl -4-hydroxybenzyl amine,

N- (p-octylphenyl) -N- 3ethyl-5-tert-butyl-4-hydroxybenzyl) amine,

and the like.

A preferred embodiment of this invention relates to the use of 3 ,5 -dialkyl-4-hydroxybenzyl amines in which at least one of R and R is an alkyl group as above-defined. The compositions of this embodiment are extremely effective antioxidants for oxygen-sensitive oils. These are illustrated by such compounds as N-methyl-N- 3 ,5 -diisopropyl-4-hydroxybenzyl amine,

N-octyl-N- 3 -methyl-5 -tert-butyl-4-hydroxyb enzyl) amine,

N- 2-dodecyl) -N- 3 ,5 -di- Z-hexyl) -4-hydroxybenzyl) amine,

N,N-diethy1-N( 3-isopropyl-5-tert-butyl-4-hydroxybenzyl) amine,

N ,N-di-butyl-N- 3 ,5-diisopropy1-4-hydroxybenzyl) amine,

N-methyl-N-ethyl-N- 3,5-di- (Z-octyl -4-hydroxybenzyl) amine,

N sec-butyl-N-dodecyLN- 3,5 -diisopropyl-4-hydroxybenzyl) amine,

N-propyl-N,N-bis- 3 -methyl-5-tert-butyl-4-hydroxybenzyl) amine,

N- sec-amyl -N,N-bis- 3,5-di-sec-butyl-4-hydroxybenzyl) amine,

N-decyl-N,N-bis- 3-ethyl-5- 3 -clecyl) -4-hydroxybenzyl amine,

and the like.

Another preferred embodiment of this invention is the use of 3,5-diallqyll-hydroxybenzyl amines in which at least one of R and R is an alkyl group as above-defined and R and R are both tertiary alkyl groups containing from 4 to 12 carbon atoms. These latter compounds contribute outstanding effectiveness in conjunction with a phosphonate as antioxidants for a wide variety of oxygensensitive oils, such as lubricating oil, transformer oil, turbine oil, gear oil and the like. These benzyl amines are illustrated by such compounds as N-heptyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl amine;

N-isopropyl-N- 3 5-di-tert-amyl-4-hydroxybenzyl) amine;

N-nonyl-N- (3 -tert-butyl-S-tert-amyl-4-hydroxybenzyl) amine;

N,N-diisobutyl-N- 3,5 -di-tert-amyl-4-hydroxybenzyl) amine;

N,N-dioctyl-N-(3,5-di-(1,1,3 ,3-tetramethylbutyl -4- hydroxybenzyl) amine;

N-propyl-N-amyl-N- 3 ,5-di-( l,1,2,2-tetramethyl propyl -4-hydroxybenzyl) amine;

N-methylN,N-bis- 3,5 -di-tert-arnyl-4-hydroxybenzyl amine;

N-heptyl-N,N-bis- 3 ,5 -di-tert-amyl-4-hydroxybenzyl) amine;

N-undecyl-N,N-bis- 3-tert-butyl-5-tert-amyl-4-hydroxybenzyl) amine,

and the like.

The most particularly preferred benzyl amines for use in this invention are compounds described above in which R and R are tertiary butyl groups, and in Which at least one of R and R is a lower alkyl group, that is, an alkyl group containing from 1 to 6 carbon atoms.

The most particularly preferred benzyl amines used in this invention comprises such compounds as N- methyl N (3,5 di tert butyl 4 hydroxybenzyl) amine; N ethyl N-(3,S-di-tert-butyl-4-hydroxybenzyl) amine; N butyl N-(3,S-di-tert-butyl-4-hydroxybenzyl)- amine; N iso hexyl N-(3,5-di-tert-butyl-4-hydroxybenzyl) amine; N,N-dimethyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine; N,N di propyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl) amine; N methyl N ethyl-N-(3,5-di-tertbutyl-4- iydroxybenzyl) amine; N ethyl-N,N-bis-(3,5-ditert-butyl-4-hydroxybenzyl) amine; N-butyl-N ,N-bis- 3 ,5 di tert butyl-4-hydroxybenzyl) amine; N -tert-amyl-'N,N= bis (3,5 di tert-butyl-4-hydroxybenzyl)amine, and the like.

The phosphonates applicable to the present invention have the formula where R and R are organic groups containing carbon and hydrogen and which may contain halogen, and X, X and X" are selected from the group consisting of oxygen and sulfur. Representative of these compounds are: di-n-butyl phosphonate, diisopropyl phosphonate, dioctyl phosphonate, bis(2-ethylhexyl)phosphonate, disec-butyl phosphonate, diisobutyl phosphonate, di-tertbutyl phosphonate, bis(1,3-dimethylbutyl)phosphonate, diamyl phosphonate, bis (2-chloro 1-methylethyl)phosphonate, ditolyl phosphonate, diethyl phosphonate, bis- (fl-chloroisopropyl) phosphonate, O,S-dimethyl thiophosphonate, diphenyl phosphonate, ditolyl thiophosphonate, (tolyl) (isooctenyl) phosphonate, ditolyl phosphonate, dimethyl phosphonate, and methyl tolyl phosphonate. In general, these compounds have from 1 to about 12 carbon atoms in each organic group represented by R and R in the above formula. These organic groups may be all-cyl, aryl, aralkyl, or alkaryl and 4 may comprise only carbon hydrogen or may contain in addition, halogen.

The dialkyl hydrogen phosphonatcs are preferred since compositions giving outstanding antioxidant effectiveness result from their employment. Another preferred class of phosphonates within the scope of this invention are these compounds represented by the above formula in which X, X and X" are oxygen. These are preferred since although they are not remarkably ei'iective antioxidants in their own right, they have shown outstanding synergistic effectiveness When employed with the above defined benzyl amines.

The additive combinations of this invention find im portant utility as antioxidants in a wide variety of oxygen sensitive materials; thus, liquid and solid products derived from petroleum crude are found to possess greatly increased storage stability by the use of an antioxidant of this invention. For example, gasoline, jet fuel, kerosene, fuel oil, turbine oils, insulating oils, motor oils and various waxes have increased oxidative stability when they contain an antioxidant of this invention. Likewise, liquid hydrocarbon fuels which contain organornetallic additives such as tetraethyllead and other organometallic compositions which are used as fuel additives attain appreciably increased oxidative stability by the practice of this invention. Furthermore, such fuels which contain halogen and phosphorus-containing scavengers for these organometallic compounds are benefited by the practice of this invention. In addition to increased storage sta bility, lubricating oils and functional fluids, such as automatic transmission and hydraulic fluids, both those derived from naturally occurring hydrocarbons and those synthetically prepared, achieve a high degree of resistance to oxidation during use at elevated temperatures by the practice of this invention. It has been found that lubricating oils may be employed at extremely high temperatures without undergoing oxidative degradation when protected by an antioxidant of this invention. The addition of small quantities or the compositions of this invention to such materials as hydraulic, transformer and other highly refined industrial oils as well as crankcase lubricating oils and lubricating greases prepared from these oils by the addition of metallic soaps, greatly increases their resistance to deterioration in the presence of air, oxygen or ozone. Furthermore, the organic soaps used in the preparation of lubricating greases are themselves stabiliz'ed by the practice of this invention.

Organometallic compositions such as tetraethylleadand tetraethyllead antiknock fluids containing halohy drocarbon scavengers, dyes and which may contain vari ous phosphorus compounds and other organometallic additives are stabilized against deterioration during storage by the addition thereto of an antioxidant quantity of the compositions of the invention.

The compositions of this invention are also extremely effective antioxidants for elastomers including high molecular weight unsaturated hydrocarbon polymers bfilh derived from naturally occurring sources and those synthetically prepared. Thus, natural rubbers and synthetic rubbers, including oil extended rubbers and sulfur vulcanized rubbers are greatly benefited by the practice of this invention. Examples of the synthetic rubbers protected by the practice of this invention include such synthetics as polybutadiene, methyl rubber, polybutadiene rubber, butyl rubber, GR-S rubber, GR-N rubber, piperylene rubber and dimethylbutadiene rubber.

The practice of this invention is also useful in protecting parafiin and micro-crystalline petroleum waxes: against the oxidative deterioration which leads to rancidity. Furthermore, the compositions of this invention are: extremely useful in the stabilization of fats and oils of animal or vegetable origin which become rancid during; periods of storage due to oxidative deterioration. Typical animal fats benefited by thepractice of this invention include butter fat, lard, beef tallo vv, fish oilssuch as cod liver oilas vell as various foods containing or prepared in animal fats which tend to deteriorate. These include, for example, potato chips, fried fish, donuts, crackers, and various types of pastry such as cakes and cool es. Furthermore, fat fortified animal feeds and fish n is used as annual feeds are greatly benefited by the practice of this invention. Not only are these compositions protected against oxi ative deterioration but the inclusion of a composition of this invention in such materials inhibits the degradation of vitamins A, D and E and co n of the B complex vitamins. Examples of composit ns containing oils derived from vegetable sources which are benefited by the practice of this inven tion include castor oil, soy bean oil, rapeseed oil, coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, citrus oils, cottonseet oil and various compositions containing these including peanut butter, peanuts and other Whole nuts, salad dressings, margarine and other vegetable shortenings.

The compositions of this invention are also outstanding antioxidants for various organic compounds and polymeric materials including polystyrene, polyvinylchloride, polyvinyl acetate, various epoxide resins and polyester resins and polymers including the alkyds. However, in particular the compositions of this invention are outstanding antioxidants for saturated hydrocarbon synthetic polymers derived from polymerization of an aliphatic monoolefin hydrocarbon compound having preferably up to 5 carbon atoms and only a single unit of unsaturation per monomeric molecule. Examples of such monomers include ethylene, propylene, butylene, isobutylene, 2-methyl4-butene, 2-methyl-3 butene and the like. Thus the polymers are homopolymers and copolymers of ethylene, propylene, butylene, isobutylene and the pentenes and usually solid. Polyethylene and polypropylene are preferred polymers in the practice of this invention and they are derived from the polymerization of ethylene and propylene respectively.

An aspect of this invention comprises premixing the benzyl amine and organic phosphonate prior to addition to the organic material to be protected. Thus, an embodiment of this invention is a composition comprising from about 0.067 to about 1000 parts by weight of a benzyl amine for each part of phosphorus as an organic phosphonate.

A preferred embodiment of this invention involves providing a lubricating oil normally susceptible to oxidative deterioration containing, in amount sufiicient to inhibit such deterioration, a small quantity of the above combination of additives. It has been found in actual practice that small amounts of these mixtures very effeotively stabilize lubricant con1positionse.g., petroleum hydrocarbon oils and synthetic oilsagainst oxidative deterioration.

To prepare the preferred lubricants of this invention,

appropriate quantities of benzyl amine and phosphonate are blended with the base oil to be protected. Suitable base oils include mineral oils and also synthetic diester oils, such as sebacates, adipates, etc., which find particular use as aircraft instrument oils, hydraulic and damping fluids, and precision bearing lubricants. All of these base oils are normally susceptible to oxidative deterioration, especially at elevated temperatures.

The finished lubricants of this invention have much greater oxidation stability and many other improved performance characteristics as compared with the corresponding base oils. In the case of lubricating oils of this invention, spectacular improvements are afforded, including markedly reduced engine wear characteristics, greatly improved oxidation stability and greatly reduced bearing corrosion properties.

The following examples illustrate various specific embodiments of this invention. The physical characteristics of the illustrative oils used in Examples 16 are as shown in Table I.

0 TABLE I Properties of Representative Petroleum Hydrocarbon Oils Oil A B O D l E i F Gravity at API 30. 3 30. 5 28. 8 31.1 20. 5 31.0 Viscosity, Saybolt:

Seconds at 100 F. 178.8 373. 8 300. 8 169. 0 249. 4 335.4 Seconds at 10 F 52 0 58 4 03 l 51. 5 45 7 (N 4 Viscosity Ind Pour Point Flash Point 410 465 365 38-5 Sulfur, Percent 0.2 0.3 0.3 0.3 0.3 0.1

With 100,000 parts of Oil C is blended 500 parts (0.5 percent) of N,N-dimethyl-N(3-isopropyl-5-tert-butyl-4 hydroxybenzyDamine and 0.025 part of phosphorus as didodecyl phosphonate. The resulting oil possesses enhanced resistance against oxidative deterioration.

EXAMPLE 4.

To 100,000 parts of Oil D is added 1000 parts (1.0 percent) of N methy1-N-(3,S-di-tert-octyll-hydnoxybenzyl) amine and 0.5 weight percent phosphorus as diisobutyl phosphonate. The resulting oil is found to possess enhanced resistance against oxidative deterioration.

EXAMPLE 5 With 100,000 parts of Oil E is blended 5000 parts (5 percent) of N-(2,6-diet1hylphenyl)-N,N-bis-(3,5-diiso propyl-4- l1ydroxybenzyl) amine and 1.5 Weight percent phosphorus as di-amyl phosphonate. After mixing, the resulting oil possesses enhanced resistance to oxidation.

EXAMPLE 6 To 100,000 parts of Oil F is added 250 parts (0.25 percent) of N-benZyl-N,N-(3,5-di-tent-butyl-4-hydroxybenZyDarnine and sufficient dimethyl-phosphonate to give 0.2 percent phosphorus. The resullting oil possesses greatly enhanced rmistance against oxidative deterioration.

The additive combinations of this invention effectively stabilize such lubricating and industrial oils as crankcase lubricating oils, transformer oils, turbine oils, transmission fluids, cutting oils, gear oils, industrial oils, mineral White oils, glass annealing oils, and, in general, engine and industrial oils which are derived from crude petroleum and are normally susceptible to deterioration in the presence of air, particularly at elevated temperatures and most particularly in the presence of iron oxide.

In the lubricating oil compositions of this invention ellective use can be made of other additives which are known to the art, such as detergent-dispersants, pour point depressants, viscosity index improvers, anti-foam agents, rust inhibitors, oiliness or film strength agents, dyes, and the like. Typical of the detergent additives that can be used in the compositions of this invention are metallic soaps of high molecular Weight acids, such as aluminum naphthenates, calcium phenyl stearates, calcium alkyl salicylates, alkaline earth metal petroleum sulfonates, alkaline earth metal alkyl phenol sulfides (barium amyl phenol 7 sulfide, calcium octyl phenol disulfide, etc), metal salts of wax-substituted phenol derivatives, and the like. Of the viscosity index imp-rovers and pour point depressants, effective use can be made of polymers of the esters of moth-- acrylic acids and gher fatty alcohols and the correspond--- ing polymers of esters of acrylic acid and higher fatty alcohols. These and other additives which can be em ployed in the compositions of this invention will now be; well known to those skilled in the art.

The antioxidant mixtures of this invention are also useful as additives to functional fluids and automatic transmission fluids. The primary constituent of a func-- tional fluid is a refined mineral lubricating oil having carefully selected minimum viscosity of 49 Saybolt Universal. seconds (SUS) at 210 F. and a maximum viscosity of 7,000 SUS at F. generally a distillate oil, lighter than. an SAE 10 motor oil. The oil usually amounts to between about 73.5 to about 97.5 percent by Weight of the: finished fluid. Preferably, the base oil is selected from a. parafiin base distillate such as a Pennsylvania crude.

The fluids usually contain compounds which are char-- acterized by containing one or more organic components which may be alkyl, aryl, alkaryl or aralkyl groups that: are bonded to one or more metal atoms through coupling; groups such as sulfonate, hydroxyl, carboxyl and mercaptan. The metal atoms may be aluminum, calcium, lithium, barium, strontium and magnesium. The organic: components contain oil solubilizing groups such as high molecular Weight straight or branched chain paraffins, aromatic or naphthenic rings, or contain a halogen. These metal compounds are present in the compounded. fluid in a concentriation range of between about 0.1 to about percent by weight. These compounds includealkaline-earth metal salts of phenyl-substituted long chain. fatty acids, alkaline-earth metal salts of the capryl or octyl esters of salicylic acid, the alkaline-earth metal salts of petroleum sulfonic acids, the alkaline-earth metal salts. of alkyl-substituted phenol sulfides, the salts of aluminum or the alkaline-earth metals with cetyl phenol, and the metal salts of wax-substituted phenol derivatives. An-

other class of additives are the so-called overbased phemates and sulfonates, which can be prepared by reaction between an alkyl phenol or alkyl phenol sulfide and an alkaline-earth metal oxide or hydroxide at an elevated temperature. The overbased phenate formed from the reaction contains up to two or three times as much metal as the normal phenate.

In addition, functional fluids may contain additional components which improve the properties of the fluid. Typical components and their concentration range in the fluid are as follows:

From about 1 to about 5 percent of an anti-Squawk additive, usually a sulfurized oil, such as sulfurized sperm oil, sulfurized lard, sulfurized vegetable oil, sulfurized glyceride, or a sulfurized ester of fatty acids.

From about 0.05 to about 2 percent of a pour point depressant. Typical types of additives are wax-substituted naphthalenes, esters of wax-substituted phenol, polymerized unsaturated esters and acrylic polymers such as polymerized esters of methacrylic acid.

About 0.005 to about 0.1 percent of a foam inhibitor. Foam inhibitors include fatty acids and fatty acid esters, pine oil, alkyl lactates, higher ethers such as 2-(di-tertamyl phenoxy) ethanol and mixtures of materials such as glycerol and sodium bis (Z-ethylhexyl)sulfosuccinate.

From about 0.03 to about 0.1 percent of a rust preventive such as carboxylic acid derivatives including alkylated succinic acid, esters and partial esters of diand polycarboxylic acids, esters and partial esters of hydroxy-substituted diand polycarboxylic acids and alkyl-substituted acids containing at least two carboxylic acid groups joined by nitrogen, oxygen or sulfur esters of acids derived from oxidized petroleum; amine derivatives including hydroxy amines, hydroxy amidines, amine salts of partial esters of phosphorus acids, hydroxy amine salts of oxidized petroleum acid hydroxy amine salts of fatty acids and long chain alkyl amines; organic sulfonates; long chain alkyl ketones; organic phosphates and phosphites; morpholine derivatives and phosphatides including lecithin and fatty acids.

About 0.1 to about 2 percent of an extreme pressure agent. These include organic compounds containing chlorine, phosphorus and sulfur, such as chlorinated waxes or a P S -terpene reaction product; organic phosphates and phosphites such as for example, tricresylphosphate or a zinc di-alkyl dithiophosphate and lead soaps such as lead naphthenate.

From about 0.05 to about 0.2 percent of a metal deactivator. Such compounds include complex organic nitrogen and sulfur-containing compounds, as for example, amines and sulfides. Also included are such compounds as organic dihydroxyphosphines, trialkyl and triaryl phosphites, certain diamines and soaps containing a metal such as tin, nickel, chromium, thallium or titanium.

From about 1 to about 10 percent of a viscosity index improver such as a polymerized olefin or isoolefin, butylene polymer or alkylated styrene polymer.

The following examples show typical functional fluids of this invention. The fluids are formed by mixing the ingredients together, while heating the oil to a temperature up to 200 F.

EXAMPLE 7 A fluid of this invention is prepared by blending parts of a conventionally-refined Pennsylvania mineral oil (99 SUS at 100 F), 2 parts of N,N-dimethyl-N-(3- methyl-5-tert-butyl-4-hydroxybenzyl)amine, suflicient diphenyl phosphonate to give 1.0 percent phosphorus in the finished composition, 5 parts of barium petroleum sulfonate, 10 parts of a polyacrylate having a molecular weight of approximately 7,000 derived from a fatty alcohol such as cetyl or lauryl alcohol, 0.1 part of a dirnethylsilicone polymer anti-foam agent, 2 parts of a dialkyl zinc dithiophosphate and 0.9 part of a dark, viscous liquid having a viscosity of 560 SUS at 210 F., a flash point of 420 F., a pour point of 30 F. and a specific gravity at 60/60 F. of 0.919.

EXAMPLE 8 Another such fluid consists of parts of a solventrefined, light acid-treated, clay-contacted, solvent dewaxed paraflin base distillate mineral oil (110 SUS at F.); 0.1 part or" N,N-dimethyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)amine; 0.01 percent phosphorus as dihexyl phosphonate; 0.1 part of calcium octyl phenol sulfide; 2 parts or a sulfurized sperm oil having a sulfur content between 10-12 percent, a viscosity of 210 F. of 200 SUS and a pour point of 65 F.; 0.3 part of an ester of an aromatic acid and wax-alkylated phenol having a molecular weight of approximately 450; 2.5 parts of a linear pale color isobutylene polymer of a controlled molecular weight havgovisjgoziftyggjtlw SUS at 210 F., a specific gravity EXAMPLE 9 An automatic transmission fluid is by mixhw 9'7 percent of an oil blend comprising 59.0 parts of a solventextractcd, Coastal oil, 4-0 SUS at 210 F; 2.0 uarts of Nme-thyl-N,N-bis-(3,5-di-tert-butyl 4 hydroxyhenzyD- amine; 0.75 weight percent phosphorus as diheptyl phosphonate; 1.0 part of a barium phenol sulfide containing 2.4 percent barium, 2 percent calcium and 3.5 percent sulfur, having a viscosity of 126 SUS at 210 F., a flash point of 430 F, a pour point of 10 F. and a specific grlavity 60/60 F. of 0.97; 1.0 part of sulfurized sperm o1 EXAMPLE 10 96 parts of a conventionally-refined Pennsylvania mineral oil (99 SUS at 100 F); 0.5 weight percent phos phorus as dimethylphosphonate; 1.5 parts of N,N-dlmethyl N (3,5di-tert-butyl-4-hydroxybenzyl)amine; 2 parts of a mixed barium phenol sulfide-calcium sulfonate 9 containing 5.7 percent barium, 0.68 percent calcium and 2.9 percent sulfur, having a viscosity of 92 SUS at 210 R, a flash point of 410 F., a pour point of 10 F. and a specific gravity 60/ 60 F. of 0.988 are blended into an effective fluid of this invention.

The synthetic lubricants which are enhanced by the practice of this invention are, in general, non-hydrocarbon organic compositions; i.e., organic compositions which contain elements other than carbon and hydrogen. EX- amples of general classes of material which are protected against oxidative deterioration by the practice of this invention include diester lubricants, silicones, halogen containing organic compounds including the fluorocarbons; polyalkylene glycol lubricants, and organic phosphates which are suitable as hydraulic fluids and lubrican 5. The synthetic diester oils stabilized by the practice of this invention include sebacates, adipates, etc., which find particular use as aircraft instrument oils, hydraulic and damping fluids, and precision bearing lubricants. These diester oils are exceedingly difficult to stabilize under high temperature conditions. In this invention, use can be made of a wide variety of diester oils of the type described in Industrifl and Engineering Chemistry, 39, 484-91 (1947). Thus, use can be made of the diesters formed by the esterification of straight or ain dibasic acids containing from 4 to about 16 carbon atoms with saturated aliphatic monohydric alcohols containing from l to about 10 carbon atoms. Of these diester oils, it is preferable that the alcohol used in their preparation be a branched chain alcohol because the resultant diesters have very valuable lubricating properties and the inhibitor of this invention very effectively stabilizes these materials against oxidative deterioration. Thus, use can be made of oxalates, malonates, succinates, glutarates, adipatcs, pimelates, suberates, azelates, sebacates, etc.

The diester lubricants used in the lubricant compositions of this invention have the formula:

COOR;

where R is an aliphatic hydrocarbon radical which may be saturated or unsaturated and has from 2 to 14 carbon atoms and R and R are straight or branched chain alkyl groups. The dicsters utilized in the preferred lubricant compositions, include esters of succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acid. Typical examples of such esters are diisooctyl azelate, di(2-ethylhem Dsebacate, di-sec-amyl sebacate, diisoootyl adipate, di(2-ethylhexyl)adipate, di(2-ethylhexyl)azelate, di(lmethyl 4 etryloctynglutarate, dllSOZlitlYl adipate, di(2- ctl ylheXyDglutara-te, di(2-ethylbutyl)adipate, ditetradecyl sebacete and di(2-ethylhexyl)pinate.

The preferred diesters are generally prepared by esterifying one mole of a dicarboxylic acid having the genral formula:

HOOC(CH COOH .c'ned chain alcohol containing at least 4 carbon atoms. ical are the reactions of succinic, glutaric, adipic, pirnelic, suberic or azelaic acid with sec-amyl alcohol, 3- ethyl butanol, Z-ethyl hexanol or the branched chain secondary alcohols undecanol or tetradecanol.

The preferred diester lubricant fluids have molecular weights ranging from about 300 to about 600 and freezing and pouring points from about 40 to less than about l00 F. Their flash and fire points range from about 300 F. to about 500 F. and their spontaneous ignition temperatures range from about 100 to about 800 F. The diesters made by reacting a dicarboxylic acid with a branched chain alcohol have been found to have superior viscometric properties as compared with diesters made by reacting dihydric alcohols with mono-carboxylic acids and thus, diesters prepared by the former method are 10 preferred in formulating the lubricant compositions of this invention.

The diester oils may be formed by the reaction of a polycarboxylic acid with a mono-hydric alcohol, the reaction of a polyhydric alcohol with a mono-carboxylic acid, reaction between a polyhydric alcohol with a polycarboxylic acid, or combinations of the above reactions; for example, reaction of a polycarboxylic acid with glycol and a mono-hydric alcohol, reaction of a glycol With a polycarboxylic acid and a mono-carboxylic acid, or the reaction of a glycol, a mono-hydric alcohol, a polycarboxylic acid and a mono-carboxylic acid. The acids may be mono-carboxylic aliphatic acids such as, propionic acid, valeric acid, Z-ethyl enanthic acid, 2,2-dipropyl butyric acid or 3-(2-methylheXyl) valeric acid. They contain unsaturated linkages, such as, in senecioic acid, sorbic acid, or angelic acid; they may be polycarboxylic aliphatic acids such as succinic acid, glutaric acid, azelaic acid, S-octene-1,8-dicarboxylic acid, or 3-hexene- 2,3,4-tricarboxylic acid, and they may be aromatic or cycloaliphatic acids, such as cyclohexanoace-tic acid, 1,4- cyclopentylenebis acetic acid, phthalic acid, hemimellitic acid, and tcrephthalic acid.

The alcohols used in preparing the polyester lubricant base materials may be aliphatic mono-hydric alcohols such as propanol, 2-ethyl-3-hexenol, 2-cthyl-4-propyl heptanol, Z-butenol, or Z-methyl propanol. They may be polyhydric aliphatic alcohols, such as Ldhexamethylenc glycol, 1,1{l-decamethylene glycol, 2-hexene-l,6-diol, and 1,6-heptylcne glycol, and they may be mono or polyhy ric alicyclic or aromatic alcohols, such as 4-[m-(2- hycroxyethyDphenyl] butanol, 3- Z-hydroxyethyl) cyclohezrancbutanol, p-(hydrorrymethyl)phenethyl alcohol, OL- methyl p Xylene-a,a-diol, 1,4-cyclohexanc-e,CK-diethyI- dimethancl, 2,3-bis( l-hydr-oxybutyllbenzyl alcohol, 4,4- [Z-(B-hydroxyhexyl) o phenylene1dibutanol, and 5-[3- (E-hydroxypropyl)cyclopenta 2,4- dienylene13-ethyl amyl alcohol.

Another class of synthetic lubricants which achieve enhanced oxidative stabi ity by the practice of this inve tion includes the silicone lubricants. The term silicone as used in the specification and claims of this application is defined as a synthetic compound containing silicon and organic groups. in naming specific compounds, the nomenclature system recommended by the American Chemical Society Committee on Nomenclature, Spelling, and Pronunciation (Chem. Eng. News, 24, 1233 (194-6)) will be used. Thus, the compounds which have the $iOSi linkages are the siloxancs. Derivatives of silane, SiH in which one or more of the hydrog us in silane are replaced with organic groups are termed the silanes. Silicates and silicate ester compounds are named as oxy derivatives of silane and are called alkoxy or aryloXy silanes.

The silicone oils and greases serving as the base medium for the lubricant compositions of the invention include the polysiloXane oils and greases of the type, polyalkyl-, polyaryl-, polyall;oxy-, and polyaryloxy-, such as po-lydimethyl siloXane, polymethylphenyl siloxane, and polymethoxyphenoxy siloxane. Further included are sili cate ester oils, such as totraalltyloxy and tetraaryloxy silanes of the tetra-Z-ethylhexyl and tetra-p-tert-buty phenyl types, and the silanes. Also included are the halogen substituted siloXanes, such as the chlorophenyl polysiloxanes.

The polyalkyl, polyaryl, and polyalkyl polyaryl silo anes are the preferred types of base medium for the silicon-containing lubricant compositions of the invention because of their high oxidative stability over a wide temperature range. The polyalltyl siloxanes, such as the dimethyl polysiloxanes, are slightly preferred over the polyaryl, and polyalltyl polyaryl siloxanes because they show the least change in viscosity over a Wide temperature range.

Certain halogen containing organic compounds have physical properties which render them particularly Well suited as lubricants. Ordinarily, the halogen is either chlorine or fluorir Typical of the chlorinated organic compounds suitable as lubricants are the chlorodiphenyls, chloronaphthalenes, chlorodiphenyl oxides and chlorinated paraffin waxes.

The fluorocarbon lubricants Which are enhanced by this invention are linear polymers built up of a recurring unit which is The fluorocarbon oils and greases are very stable chemically and have high thermal stability. These desirable physical properties appear to be closely related to the bond distances occurring in the fluorocarbon polymeric molecule, which may also contain chlorine bonded to carbon.

Polyalkylene glycol lubricants which are benefited by the practice of this invention are ordinarily the reaction product of an aliphatic alcohol with an alkylene oxide. The preferred a kylene oxides are ethylene oxide and propylene oxide. Depending upon the alcohol employed and the molecular Weight of the compound, the polyalkylene glycol lubricants may be either water insoluble or water soluble. The molecular weights of these polymers may vary from about 400 to over 3,000. In general the polyalliylene glycol lubricants are characterized by high viscosity indices, low APE gravities, low pour points and they have the general formula:

where n is a small integer and depends upon the alkylene oxide employed and x is a large integer from about to about 100 depending upon the molecular weight of the finished lubricant and R represents the hydrocarbon group derived from the particular aliphatic alcohol employed.

Another important class of synthetic materials which are enhanced by the practice of this invention are phosphate esters which are, in general, prepared by the reaction of an organic alcohol with phosphoric acid and have the general formula:

where R, R and R represent either hydrogen or an organic radical and where at least one of the groups represented by R, R and R" is an organic radical. Typical of these materials is tricresylphosphate. The phosphate esters are in general characterized by excellent fire resistant properties and high lubricity. However, their thermal stability is such that they are ordinarily unsuited for high temperature applications above about 300 F. Other examples of phosphate esters include: tris(2-chloro- 1 -methylethyl phosphate; tri-n-butyl-phosphate; tris 2 ethylhexyl) phosphate; triphenyl phosphate; tris(p-chlorophenyl) phosphate; diethyl-m-tolyl phosphate; p-chlorophenyl dimethyl phosphate; tris(Z-n-butoxyethyDphmphate; dimethyl-m-tolyl phosphate; di-n-propyl-m-tolyl phosphate; di-n-but l phenyl phosphate; 1,3-butylene-B- chloroisopropyl phosphate; methyl-di-m-tolyl phosphate; bis(2-chloro-l-methylethyl)-m-tolyl phosphate; dimethyl 3,5-xylyl phosphate; 4-cl'1loro-n-tolyl dimethyl phosphate; Z-ethyl-l-n-propyltrimethylene methyl phosphate; 4- chloro-rn-tolyl l-methyltrimethylene phosphate; dimethyln-octyl. phosphate, and the like.

The synthetic base greases used in formulating lubricant compositions of the invention are formed by admixing a soap with an oil of any of the types described above. Such soaps are derived from animal or vegetable fats or fatty acids, wool grease; rosin, or petroleum acids. Typical examples are lead oleate, lithium stearate, aluminum tristcarate, calcium glycerides, sodium oleate and the like. In addition, the polyester greases may contain unreacted fat, fatty acids, and alkali; unsaponifiable matter including glycerol and fatty alcohols; rosin or wool grease; water; and certain additives which may function as modifiers or peptizers.

In formulating the grease compositions of this invention, greases prepared by admixing a lithium soap with the polyester oils are preferred as they have superior oxidative stability as compared with greases formulated with other soaps, such as the sodium, calcium or lead soaps.

In preparing the improved lubricant compositions of this invention, an appropriate quantity of benzyl amine and phosphonatc are blended with the diester oil to be stabilized. lf desired, preformed concentrated solutions of the stabilizer in the base lubricant can be prepared and then subsequently diluted with additional lubricant to the desired concentration. An advantage of this invention is the fact that the additives are easily and rapidly blended with the base oil. An additional advantage of this invention is that the additives are compatible with the usual additives that are frequently used to fortify lubricant cornpositions, such. as detergent-dispersants, viscosity index improvers, dyes, anti-rust additives, anti-foaming agents and the like.

The following examples illustrate various specific embodiments of this invention.

EXAMPLE 11 With 100,000 parts of di-(sec-amyl)sebacate having a viscosity of 210 F. of 33.8 Saybolt Universal seconds (SUS), a viscosity index of 133 and a molecular weight of 342.5 is blended 100 parts (0.1 percent) of N,N-dipropyl-N-(3,5-diisopropyl 4- hydroxybenzyl)amine, and 0.05 weight percent of phosphorus as diarnyl phosphonate. T he resulting diester lubricant possesses greatly enhanced resistance against oxidative deterioration.

EXAMPLE 12 To 100,000 parts of di-(2-ethylhexyl)sebacate having a viscosity at 210 F. of 37.3 SUS, a viscosity index of 152 and a molecular weight of 426.7 is added 1000 parts (1 percent) of N,N-di-dodecyl-N-(3,S-di-tert-butyl-4-hydroxybenzyl)amine, and 0.3 weight percent phosphorus as disec-hexyl phosphonate. After mixing, the resultant diester lubricant possesses greatly enhanced oxidation resistance.

EXAMPLE 13 To 100,000 parts of di-(Z-ethylhexyl)adipate having a viscosity at 210 F. of 34.2 SUS, a viscosity index of 121 and a molecular weight of 370.6 is added 2000 parts (2 percent) of N,N-dioctyl-N-(3-methyl-5-tefl-amyl-4-hydroxybenzyl)amine, and 1.2 Weight percent phosphorus as di-dodecyl phosphonate. After mixing, the resultant diester lubricant possesses outstanding resistance against oxidative deterioration.

EXAMPLE 14 Three parts of N,N-diphenyl-N-(3-rnethyl-5-tert-butyl- 4-hydroxybenzyl)amine, and 0.75 weight percent phosphorus as diethyl phosphonate, are blended and mixed with 197 parts of a grease comprising 12.5 percent of lithium stearate, 1 part of polybutene (12,000 molecular weight), 2 percent of calcium xylyl stearate and 84.5 percent of di(2-ethylhexyl)sebacate, to prepare an improved grease of this invention.

EXAMPLE 15 Blended with 750 parts of diisooctyl adipate having a viscosity of 35.4 SUS at 210 F, a viscosity of 57.3 SUS at 100 F., a viscosity of 3.980 SUS at F, a viscosity of 22,500 at F; a viscosity index is 143, its ATSM pour point is below F. and its specific gravity (60 P./60 P.) is 0.926, are one part of N,N- dimethyl-N-( 3 ,5-di-tert-butyl-4-hydroxybenzyl) amine and 0.5 part of phosphorus as di-sec-butyl phosphonate.

13 EXAlNIPLE l6 Thirty parts of N,N-dihexyl-N-(3-ethyl-5-tert-amyl-4- hydroxybenzyl)amine and 50 parts of phosphorus as dimethyl phosphonate are mixed with 10,000 parts of a grease comprising 11 percent of lithium stearate, 1 percent or polybutene (12,000 molecular weight), 1 percent of sorbitan monooleate, 86.6 percent of di[1-(2-methylpropyl)-4-ethyloctyl] sebacate.

EXAMPLE 17 One part of N-methyl-N,N-bis-(3-methyl-5-tert-butyl- 4-hydroxybenzyl)amine and 0.5 part of phosphorus as methyl ethyl phosphonate, are blended with 100 parts of a polymethylpolyphenyl siloxane grease of medium weight consistency having a penetration of 240-280 (ASTlVi- 21748) a minimum melting point of 400 F. and a serviceable temperature range of from 30 to 400 F. (This siioxane grease is sold under the trade name Dow- Corning 44.)

EXAMPLE 18 To a siloxane fluid having a viscosity of 71 centistoltes at 25 C. and 24 centistokes at 75 C., a specific gravity of 1.03 at 25 C., a freezing point of 70 C. and a flash point of 540 R, which is composed of a halogen substituted polyphenylpolymcthyl siloxane is added sufiicent N,N diethyl i l-(3-sec-butyl-5-tert-amyl-41ydroxybenzyl)amine to give a composition containing 1.5 percent of this additive and sufiicient diethyl phosphonate to give a composition containing 0.65 percent phosphorus. This oil has an extremely high degree of resistance against oxidative deterioration due to the presence of the additive of this invention.

EXAMPLE 19 To a poly(trilluorochloroethylene) having the formula (CF CFCD and an average molecular weight of 880, pour point of C. and a viscosity of 45 centistolses at 160 F. is added 1.25 percent of N,N-dirnethyl-N-(3- methyl-5-tert-butyl-4-hydroxybenzyl)amine, and sufficient dimethyl phosphonate to give one percent phosphorus to prepare an improved lubricant of this invention.

EXAMPLE 20 A composition consisting of 0.6 percent iLN-dimethyl- N-(3,5-di-tert-butylA-hydroxybenzyl)amine, and 0.3 percent phosphorus as didecyl phosphonate is prepared by blending an appropriate quantity of these compounds with a fluorocarbon grease having a penetration of 267 millimeters at 77 F, 285 millimeters at 100 F. and 300 millimeters at 125 F. (ASTM21748); and a dropping point of at least 400 F. (ASTM-D56642). This grease is commercially available under the trade name Fluorolube GR544.

EXAMPLE 21 To a polyalkylene glycol oil lubricant having a viscosity index of 148, ASTM pour point of 55 F, a flash point of 300 F., a specific gravity of 0.979 and a Saybolt viscosity of 135 at 100 F. is added one percent of N-tertbutyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)amine and 0.5 weight percent phosphorus as diisopropyl phosphonate, to prepare an extremely oxidation resistant polyallrylenc glycol lubricant.

EXAMPLE 22 An improved lubricant of this invention comprising a chlorinated organic compound is prepared by admixing 0.5 percent of N,N-dipropyl-N-(3-methyl-5-tert-octyl-4- hydroxybenzyDamine, and 0.25 Weight percent phosphorus as dimethyl phosphonate with a chlorodiphenyl oil having a distillation range of from 554 to 617 F., a Saybolt viscosity at 100 F. of about 49, a pour point of -30 F. and a specific gravity of about 1.267.

EXAMPLE 23 An improved hydraulic fluid and lubricant according to this invention is prepared by adding 2 percent of N,N- dimehyl- I-(3-methyl-5-tert-butyl 4 hydroxybenzyl) amine and one percent phosphorus as dimethyl phosphonate to tricresyl phosphate.

The benzyl amine-phosphonate mixtures of this invention very effectively enhance the oxidation resistance of such diester oils as diethyl oxalate; di-sec-butyl malonate; di (2 hexyl)succinate; di-(isoheptyl)pimelate; (ii-(3- decyl)seberate; di-sec-amyl glutarate; di-(isobutyl)gluta rate; di-(Z-ethyloutyl) glutarate; di-(Z-ethylhexyl) glutarate; di-secamyl adipate; di(3-methyl-butyl)adipate; diethyl adipate, di-Z-ethylhexyl adipate; di-sec-amyl azelate, di-(isobutyl) azelate; di-(Z-ethylbutyl) azelate; di-(Z-ethylhexyl)axelate; di-sec-amyl sebacate; di-sec-butyl sebacate; di-(Z-ethylhexyl)sebacate; tie glutarates; adipates, azelates and sebacates of branched chain secondary alcohols, such as undecanol, tetradccanol; etc., and, in general, diesters of the type described above and in the literature as useful for synthetic lubricant purposes.

In the compositions of this invention cdective use can be made of other additives which are known to the art, such as other inhibitors, detergent-dispersants, pour point depressants, viscosity index improvers, anti-foam agents, rust inhibitors, oiliness or film strength agents, dyes, and the like. Of the inhibitors which can be effectively used with synthetic lubricants in combination with the additives of this invention are suliurized sperm oil, sulfurized terpenes, sulfurized parafiin wax olefins, alltyl phenols, lecithin, neutralized dithiophonphates, phosphorus pentasulfide-terpene reaction products, diphcnylamine, phenylnaphthylamine, fi-naphthol, pyrogallol, and the like. Typical of the detergent additives that can be used in the compositions of this invention are metallic soaps of high molecular weight acids, such as aluminum naphthenates, calcium phenyl stearates, calcium alkyl salicylates, alkaline earth metal petroleum sulfonates, netal salts of waxsubstituted phenol derivatives and the like. Of the viscosity index improvers and pour point depressants, effective use can be made of polymers of the esters of meth acrylic acids and higher fatty alcohols and the corresponding polymers of esters of acrylic acid and higher fatty alcohols. These and other additives which can be employed in the compositions of this invention will now be well known to those skilled in the art.

As noted above, the antioxidant mixtures of this invention are also excellent antioxidants for saturated hydrocarbon polymers, prepared from monoolelins having up to 5 carbon atoms.

Polyethylene and polypropylene are, for example, hydrocarbon polymers derived from the polymerization of ethylene and propylene. This polymerization can be accompli-shed by a great variety of methods which lead to products of diverse properties. Polymers of any nature may advantageously be utilized for preparing compositions according to the present invention. The polymers which are employed may, for example, be similar to those which may be obtained by polymerizing ethylene in a basic aqueous medium and in the presence of polymerization laying quantities of oxygen under relatively high pressures in excess of 500 or 1,000 atmospheres at temperatures between 150 and 275 C. Or, if desired, the may be similar to the essentially linear and unbranched polymers ordinarily having greater molecular weights which may be obtained under relatively low pressures of 1 to atmospheres using such catalysts to polymerize the ethylene as mixtures of strong reducing agents and compounds of groups EVE, VB and VEB metals of the eriodic system; chromium oxide on silicated alumina; hexavalent molybdenum compounds; and charcoal supported nickel-cobalt. The polymer which results from these various polymerization processes may have a molecular weight in the range from 1300 to over 1,000,000 depending on the particular conditions of polymerization employed.

There are several methods available for preparing the inhibited hydrocarbon polymer compositions of this invention. Thus the blending of the additives of this in vention, with a polymer such as, for example, polyethylene, may be carried out on open rolls, on internal mixers or may be accomplished by mixing with extrusion. It is also possible to prepare concentrated batches of the polymer containing excessive amounts of the additive and then mix the concentrate with additional polymer to prepare a composition of this invention. The preferred method of compounding the polymers is by milling on heated open rolls at slightly elevated temperatures by methods well-known to the art. The temperature range employed is sometimes critical as certain polyethylenes will not melt at low temperatures and tend to stick to the rolls at high temperatures. The additive may be initially mixed with the polymer in the dried state or may be first dissolved in a suitable solvent, then sprayed on the polymer arid milled in.

Examples of the hydrocarbon polymer compositions of this invention prepared as described above follow. All parts and percentages are by Weight in these examples.

EXAMPLE 2-]:

To 1,000 parts of polyethylene produced by oxygen :catalized reaction under a pressure of 20,000 atmospheres and having an average molecular Weight of 40,000 is added and mixed 2 pants of -N,N-dimethyl-N-(3,5-di-tertbutyl-4-hydroxybenzyl)amine and 0.025 percent phosphorus as diarnyl phosphonate. The resulting composition has a greatly increased oxidative stabilty.

EXAMPLE 25 To 100 parts of polyisobutylene having an average molecular Weight of 100,000 is added 0.5 part of lJ-methyl N,N bis (3 methyltert-butyl-4-hydroxybenzyl)amine and 0.3 percent phosphorus as dimethyl phosphonate. The oxidative stability of the polymer is greatly increased by the addition of this compound.

EXAMPLE 26 A linear polyethylene having a high degree of crystallinity (up to 93 percent) and below one ethyl branched chain per hundred carbon atoms, a density of about 0.96

gram per milliliter and which has about 1.5 double bonds per 100 carbon atoms is treated with 50 10 roentgens of B-radiation. To the thus irradiated polymer is added 0.1 percent of hL-N-dimethyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)amine and 0.05 percent phosphorus as diisopropyl thio phosphonate. The resulting product has improved stability characteristics.

EXAMPLE 27 To a polyethylene having an average molecular weight of 1500, a melting point of 8890 C. and a specific gravity of 0.92 is added one percent of N,N-dimethyl-N- (3 -methyl-5 -te1't-butyl-4-hydroxybenzyl) amine and 0.6

percent phosphorus as dimethyl thionophosphonate. Af-

ter milling in the anitoxidant an extremely oxidation resistant product results.

EXAMPLE 28 Two parts of N,N-d-imethyl-N-(3-methyl-5-tert-butyl-4- 'hydroxybenzyllamine and 1.0 percent phosphorus as diphenyl phosphonate are added with milling to 100 pants of a low density polyethylene prepared by high pressure polymerization and which has an average molecular Weight of about 20,000. The resulting product is vastly improved in its oxidative stability.

'15 N benzyl N,N-(3,5 di tert butyl 4 hydroxybenzyllamine and 0.5 percent phosphorus as dimethyl phosphonate.

EXAMPLE 31 To an isotactic polypropylene having a tensile strength greater than 4300 p.s.i. and a compressive strength of about 9,000 psi. is added sufiicient Nmethyl-N,Nbis- (3,5-di-tert-butyl-4- tydroxybenzyD-amine to give a composition containing 1.5 percent of the benzyl amine and suflicient diisobutyl phosphonate to give 0.85 percent phosphorus.

EXAMPLE 32 To a wax-like polypropylene having a melting point above 130 C. and a molecular weight of about 4,000, a density of 0.913 is added 0.2 percent of N,N-dimethyl-N- (3-rnethyl-5-tert-butyl-4-hydroxy'benzyl)amine and 0.05 percent phosphorus as dioctyl phosphonate. The antioxidant is added to the polypropylene in the molten state and the mixture is allowed to solidify into the desired shape. A polypropylene product of outstanding oxidative stability results.

In addition to the additives of this invention saturated hydrocarbon polymers may contain other compounding and coloring additives including minor proportions of carbon black, elastomers, polyvinyl compounds, carboxylic acid esters, urea-aldehyde condensation products, flame retarding agents such as antimony trioxide and chlorinated hydrocarbons and various pigment compositions designed to impart color to the finished product.

Other hydrocarbon polymers which are stabilized against oxidative deterioration according to this invention include natural rubber, GR-S and GR-N rubbers, butyl rubber, methyl rubber, polybutene rubber, butadiene rubbers, piperylene rubbers, dirnethylbutadiene rubbers, polystyrene, polybutadiene, polyisobutylene, polyethylene, isobutylene-styrene copolymer and, in general elastomeric hydrocarbon polymers which are normally susceptible to oxidative deterioration. Such polymers are well known in the art and besides being susceptible of oxidative deterioration are characterized by having molecular Weights above about 10,000. The problem resulting from heat, light and catalyst promoted oxidative deterioration in such hydrocarbon polymers is intensified because of free radical formation within the polymers. This leads to various forms of physical and chemical degradation such as chain scission, autocatalytic oxidation, reduction in molecular Weight and loss of original physical properties. The net result is that the desirable useful and necessary properties of the polymers which are associated with their original chemical structure and molecular Weights are lost to a greater or lesser extent unless the polymers are stabilized against such deterioration.

Typical stabilized hydrocarbon polymers of this invention are illustrated by the following specific examples wherein all parts and percentages are by weight.

EXAMPLE 33 To a synthetic rubber master batch comprising parts of GR-S rubber having an average molecular weight of 60,000, 5 parts of mixed zinc propionate-stearate, 50 parts of carbon black, 5 parts of road tar, 2 parts of sulfur and 1.5 parts of mercaptobenzothiazole is incorporated 1.5 parts of N,N-dimethyl-N-(3-isopropyl-5-tert-butyl-4- hydroxybenzyDamine and 0.45 percent phosphorus as dimethyl phosphonate. This batch is then cured for 60 minutes at 45 pounds per square inch of steam pressure.

' tar, 2 parts of sulfur and 1.5 parts of mercaptobenzo- EXAMPLE 36 To a master batch of GR-N synthetic rubber comprising 100 parts of GR-N rubber having an average molecular weight of 75,000, parts of zinc stearate, 50 parts of carbon black, 5 parts of road tar, 2 parts of sulfur and 2 parts of mercaptobenzothiazole is added 2 percent based on the weight of the batch of N,N-diphenyl-N-(3-methyl- 5-tert-butyl-4 hydroxybenzyl)amine, and 0.85 percent phosphorus as di(phenylphenyl)phosphonate.

EXAMPLE 37 0.25 percent by weight of N,N-dihexyl-N-(3'-ethyl-5- ditert amyl-4-hydroxybenzyl)amine and 0.075 percent phosphorus as diisobutylphosp honate are incorporated in polybutadiene having an aver-age molecular weight of 50,000.

EXAMPLE 38 To natural rubber (Hevea) is added 0.1 percent of N,N-dimethyl-N-(3,5-di-tert butyl 4 hydroxybenzyl)- amine and 0.005 percent phosphorus as di-dodecylphosphonate.

The above examples illustrate the improved compositions of this invention. Other such compositions and the methods of preparing the same will now be apparent to one skilled in the ant.

The stabilizers of this invention are also excellent additives to tetnaalkyllead antiknock compositions. The tetraalkyllead antiknock agents which are stabilized according to this invention are represented by such compounds as tetramethyllead, tetraethyllead, tetrapropy llead, dimethyldiethylle-ad, trimethylethyllead, and the like, or mixtures thereof. Such compounds containing from 4 to about 12 carbon atoms, one atom of lead and a plurality of lead-to-carbon bonds, are capable of increasing the octane quality of gasoline when employed therein in antiknock quantities0.5 to 6.5 grams of lead per gallon. Halogen-containing compounds such as triethyllead bromide may also be stabilized according to this invention. V

The scavengers which are preferably, but not necessarily, present in the antiknock compositions of this invention are organic halide compounds which react with the lead during combustion in the engine to form. volatile lead halide. The halogen of these scavengers has an atomic weight between 35 and 80; that is, the active scavenging ingredient is chlorine and/or bromine. Such scavengers include carbon tetrachloride, propylene dibromide, 2-chloro-2,3-dibromobutane, 1,2,3-tribromopropane, hexachloropropylene, mixed bromoxylenes, 1,4- dibromobutane, 1,4-dichloropentane, [3,,8'-dibromodiisopropyl ether, li,fi'-dichlorodiethyl ether, trichlorobenzene, dibrornotoluenes, and in general those disclosed in Us. Patents 1,592,954; 1,668,022; 2,364,921; 2,479,900; 2,479,901; 2,479,902; 2,479,903; and 2,496,983. in short, the preferred scavengers contain only elements selected from the group consisting of carbon, hydrogen, bromine, chlorine and oxygen. The amount of scavenger used is from about 0.5 to about 2.0 theories, a theory beingdefined as the quantity required to react with the lead to form lead halidei.e., 2 atoms of halogen pera-tom of lead. When we use mixtures of bromine-containing and chlorine-containing scavengers, particularly bromo and chlorohydrocarbons, we can employ concentrations and proportions as described in US. Patent 2,398,281. Such concentrations are sufficient to control the amount of deposits formed in the engine.

The tetraalkyllead antiknock compositions of this invention may contain other ingredients such as dyes for identification purposes, metal deactivators, diluents and the like.

Antikn'ock compositions containing tetraalkyllead antiknock agents are employed by adding them to gasoline to improve the antiknock quality thereof. Such gasolines both before and after addition of the antiknock fluid are benefited by the practice of this invention. Thus gasolines towhich have been added a compound of this invention are found to be more stable upon prolonged periods of storage.

The following examples illustrate gasoline embodiments of this invention.

. EXAMPLE 39 To 10,000 parts of a grade 115/145 aviation gasoline containing 45 ml. of tetraethyllead per gallon which has an initial boiling point of F. and a tfinal boiling point of 330 Rand an API gravity of 71.0 is added .5

ercent of N,-N-dimethyl-N-(3,5-di-tertbutyl 4-hydroxybenzyl)a=mine and 0.4 percent phosphorus as dioctyl phosphonate.

EXAMPLE 40 To a gasoline containing 26.6 percent aromatics, 20.8 percent olefins and 52.6 percent saturates and which has an API gravity of 62.1 is added 0.1 percent of N,N-dimethyl-N-(3-methyl-5-tert-bu-tyl-4 hydroxybenzyh'amine and 0.01 percent phosphorus as diisobutyl thiophos phonate.

Similarly, other additive mixtures of this invention may be added with benefit to gasoline of whatever nature and however processed.

The additive combinations of this invention are also extremely useful in inhibiting and stabilizing non-petr'o} leum fats and oils normally subject to the deteriorating eiiect of oxidative rancidity. in particular, compounds of this invention are excellent stabilizers for aninial'fats and oils, especially lard, against the efifects of rancidity.

in formulating the stabilized non-petroleum fats and oils of this invention, the additive or combination of additives is incorporated by appropriate means into the substrate to be stabilized. Thus, in the case of animal, vegetable and fish oils, the additive or combination of additives is added in appropriate quantity and theresulting mixture agitated to insure homogeneity. Where the substrate is a solid at room temperatures-e.g., fats, butter, etc.the is preferably carried out at temperatures above the melting point of the substnat'e. When a combination of additives is used, they can be mixed with the substrate as a preformed mixture or can be sepanately blended therewith in either order. Generally speaking, it is desirable to fir'stdissolve the additive combination in high concentration in a small portion of the material to be stabilized. The resulting concentrated solution then blended with the remaining bulk. Another Way of facilitating the formulation of the composition of this invention is to pie-dissolve the additive or combination of additives in asuitable solvent, suclh'as ethanol, glycerol, propylene glycol, etc, and then mix the resultant solution with the material .to'be' stabilized. However, the preferred way of formulating the compositions ofthis invention is to pu e-dissolve the additive mixture in a fatty acidpantial ester of'a polyhydroxy compound, notably am'onoglyceride, and then blend this mixture with the material to be stabilized. The nature of these monoglyceride compositions is well known in the art and may be made from either animal or vegetable fats, with or without previous hydrogenation; These compositions generally contain about 40 percent of the monostearyl, monooleayl, and/or monopalmityl glycerides or mixtures thereof with the balance comprising'a mixture of diand tri-glycerides. Molecularly distilled monoglyc enides may also be used for this purpose. These compositions will be' apparent from the followingexamples.

9 EXAMPLE 41 With 1,000 par-ts of meltedlard mix 1 part (0.1 per cent) of N'- (2,6-diethylpheny1) -N,N- bis-( 3,5 -diisopropy1'- 4-hydroxybenzyl)amine and 0.05 percent phosphorus as diisopropylphosphona'te'. After cooling the lard can be stored for long periods of time without the development of ranoidity. A

I EXAMPLE 4 2 With 5 ,000 parts of cottonseed shortening blend 5 parts (0.1 percent) of iN-tert-butyl-N-(3,5 di-tert-butyl-4-hydroxybenzyl'.)amine and 0.1 percent phosphorus as diamyl phosphonate. The resulting shortening has improved re'sistanc'e against oxidiative rancidity.

EXAMPLE 43 To 10,000 parts of dorm oil ar e added with stirring 20 parts (0.2 percent) of N, N-dimethyl-N-(B-methyI-S tertbutyl 4 hydroxybenzyl)amine and 2 parts (002 percent) of phosphorus as dimethyl phosphonate. The resulting coin-oilbasiiriproved stora e stability characteristics.

Preparation of the'phosphonates used in this invention, such. as diis'obutyi phosphonate, di(2,4-dichlorocyclohexyl)phosphonate, di(3-chl-oro-4 methylphenyDphosphonate, etc., follows the general 'prcedures described in Industrial and Engineering Chemistry, 49, 1871 (1957).

The benzyi amine compounds used in thisinvention are white or pale yellowcrystalline solids and are soldble inwarious organic solvents andin gasolines, diesei fuels, hydrocarbonoils andthe like. T hesepompounds are further characterized by being relatively stable, easily crystal lizable materials.

The benzyl amines'are prepared by reacting a 2,6-dialkyl phenol in which one of the alkylgroups contains from 3 to 112 carbon'atoms and is branched on the alpha carbon atom and the other alkyl group contains from 1 to 12 carbon atoms; formaldehyde; and a primary or secondary amine in which the hydrocarbon portion thereof'; is in conformity with the groups designated herein above as =R and1R 'In conducting this process a monohydric alcohol containing from '1 to 6 carbon atoms is preferably used as the reaction solvent. The reaction temperature is in the order of about 20 to about 100 C. It is preferred to conduct the process within the range of aboutSQ to 90? C.

The synergistic antioxidant of ;this invention may: be pre-mixed prior to addition'to the material to be protected. Thus, an embodiment of this invention is a mixture containing from 0.005 to 100 parts of phenolic compound per part of phosphorus;

' EXAMPLE 44' Sufficient N ,N -dimethyl-N-(3,5 di-tert-buty1 4-hydronybeniy l) amineand 'bis( 2'-ethylhexyl)" phosphonate' are blended together to given composition containing 0.005 part ofthe phenol per part of phosphorus:

XA JL Q N,N 7 dimethyl N (3 rnethyl 5 tert butyl 4- hydrloxyben'z yhamine anddimethyl phosphonate are coni iindd'into' a containing 1000 parts of the ph l' of phosphorus.

7 EXAMPLE 46 A mixture containing 2.0 parts of N-'(2,6-diethylphenyl) N,N'- bis-"(3,5 diis'opropyl 4 hydroxyben- ZyDian'Jin'e per pm of phosphorus is prepared by m ixing appropriate quantities of N ('2,tS-tiiethyl-ph'e'nyl) N,-N- bis( '3,5 diisopropyl 4 hydrox-ybenzyl)amine and di-secbu-tyl phosphonate; I

' EXAMPLE 47 N,N dioctyl N (3- methyl 5 tert amyi 4- hydroxybenzl) amine and diamyl phos honate are mixed in such proportion that the resulting inixture' has '4 parts of thephenol'per part'of phosphorus.

EXAMPLE 48 To illustrate the outstanding benefits obtained by the achieved.

20 practice ofthis invention, a standard oil oxidation test is used. The equipment and test procedure described by Kroger et al., Erdol 'and Kohl, 2, page 398 (1949), served as a basis for the tests. Theequipment andprocedures are slightly modified in order to make the oxidizing conditions more strenuous; In this manner the test lubricants are subjected to severe oxidizing conditions in order to conclusively establish the eifectivenes s of ad ditive's tinder very adverse conditions. Furthermore, the modifications are found to provide results which correlated extremely well with test results of other standard procedures, including actual engine tests.

The equipment consists "of a reaction cell connected with an open end: manometer whereby the total uptake of oxygen bythe oil is determinedby noting the drop in height of the mercury in the manometer. The test oil sample is placed in the reaction cellwhichis the'nflushed With 'oxyge'n and the temperature is then raised and held at that selected for'the test until the substrate 'oil under? goes catastrophic oxidationwhich is shown by a rapid oxygen uptake. In all cases, the testoil is deliberately contanunatedUwith'iron he'xoate as an oxidation promoter. In tests ofqth'is nature, theoxidation stability of ate-st lubricant is ordinarily determined by measuring its induction per'iod,'| at i's,"the time required for" catastrophicde terioration under the above outlined conditions '}The longer the induction period, the more stable the lubricant. The oil employed in these 'test's has an induction period withno added'antioxidaiit, under the test conditions de scribedabove, of3' mi-nutes. When 1 1-o' -ma1es per liter of dimethyl phosphonate wasadded to the oil (0.037 weight percent phosphorus), the induction period did not change. "Further,'when double'this concentration (01.073 weight percent phosphorus) was added to the 'oil the induction period was still 3 minutes. In a similar test eniploying 1X10 moles per liter 'ofN,'N-dimethyl-N-(3,5- dia'tert-butyl-4-hydroxybenzyl)amme, the induction period of the oil was 189 minutes. However, when IX 10 moles per liter of each dimethyl phosphonate and; N N*-dimet hyl-N-'( 3,5 diatert butyl-4-hydroiiybenzyl) amine were addedtothe oil the induction period increased :to967 minutes. Thus, the employment of a phosphonate in conjunction with the hydr'oxybenzyl amine gave a total ly'unexpected increase in the induction period which'could not be anticipi ated from the individual actiyities of the hy 'droxybenayl amine and phosphonate alone.

- I EXAMPLE 49 To further illustrate the usefiul properties of the novel mixture or this invention, recourse is had to the Polyveriform"'oxidatioii StabilityTest as described in the paper entitled Eac'to'rs Causing Lubricating Oil Deterioration in Engines (Ind. and Eng. Chem. Anal. Ed, 117, 302 (1945) 'See also A Bearing Corrosion Test for Lubricatin'g Oils and its Correlation With Engine Performance nn; Chem.,' 21,737 1949 This test elfectively evaluates the performance of lubricating oil antioxidants. 'Ihe'test equipment'projcedure employed and correlations of theresults with engine performance are discussed in thefi'rst paper above cited. By employing various compoundsof'this' invention in oxygen-sensitive lubricating on; effective inhibition of oxidation deterioration is 7T6 demonstrate the outstanding performance of the compositions of' invention as antioxidants for industrial lubricantsconiparative tests were conducted using the method and apparatus essentially as described'in the publication first above-mentioned, One minor modificatio'nf was. that the steel sleeve and copper test piece described'in this'fpu blication were omitted from the apparatus. 'In' these tests 'aniniti-ally additive-free, V.I.solvent refi'ned SAE-lO. crankcase oil was used. The principalrte'st conditions consisted of passing 70 liters of air per'hou'r through the test oil for a total period of 20 hours while maintaining the oil at a temperature of 21 I". to make the test more representative of actual use conditions. Oxidation deterioration of the oil was further promoted by employing as oxidation catalysts 0.05 percent by weight of ferric oxide (as ferric 2-ethyl hexoate) w erein R an are yl g o p o om 1 t 2 rb droxybenzyl amine and from about 0.005 to about 1.5

and 0.10 percent by Weight of lead bromide, both of these 5 weight percent of phosphorus as said phosphonate, based amounts bemg based upon the weight of oil employed. on the weight of material to be protected. lubricating oils of this invention were prepared .by blend- 2. A synergistic antioxidant mixture consisting essenmg a r h r hone r a appropnate y xyb t lly of a 3,5dialky -4-hydr xybsn yla ine ng the zyl amine with a port on of the above lubricating oil. formula; These compositions were then subjected to the above de- 10 R5 scribed stringent oxidation test. Another portion of CH3 the same lubricating oil was tested with no added anti- HO oxidant, while still other portions were tested with the v hydroxybenzyl amine and phosphonate in the absence of R CH3 the other. The results of these tests are shown in 15 Table 11. wherein R is an alkyl group having from 1 to 4 carbon TABLE ll Efiectiveness f Phosphonates and Various 3,5-dialkyl-4- Hydroxybenzyl Amine Compounds in the Polyveriform Test Used Oil Properties Weight Weight Percent Percent Additive 3,5-dialkyl Phosphorus Percent 4-hydroxyas the Acid Viscosity Visual benzyl Designated No. Increase Rating amine Phosphonate at 100 F SUS None 0 o 5.7 107 O Dimethyl phosphonate 0 0.05 3.5 43 O N ,N-Dimethyl-N-(3,5-di-tcrt ut benzyDamine 1.0 0 4.9 71 A Dimethyl phosphoneate and N,N-dimethylN- (3,5-di-tert-butyl-thydroxybenzyl)amine 1.0 .05 0.4 6 A Di-scc-butyl phosphonate 0 0. 025 2.7 33 O Di-sec-butyl phosphonate and N ,N di1nethy N (3,5-di-tert-butylt-hydroxybenzyl)amine 1.0 0.025 1.6 16 A N,N-Dimethyl-N-(3rmethyl-5-tert-butyl4- hydroxybenzyDamine 1.0 0 5.9 135 D Di-sec-butyl phosphonate and N,N-dimethy1 N- (3-methyl-5-tert-butyl-thydroxybenzyDamine... 1.0 0.025 0.4 9 B 1 Saybolt Universal seconds.

We claim:

1. Organic material normally susceptible to oxidati-ve deterioration protected by a small antioxidant quantity of a mixture of (a) a 3,5-dialkyl-4-hydroxybenzyl amine having the formula R1 I HOCH2N I Ra Ra wherein R is an alkyl group containing from 1 to 12 carbon atoms, R is an alkyl group containing from 3 to 12 carbon atoms'which is branched on the alpha carbon atom, R is selected from the group consisting of alkyl of from one to 12 carbon atoms, cycloallcyl of from 5 to 6 carbon atoms, aralkyl of from 7 to 11 carbon atoms, aryl of from 6 to carbon atoms and alkaryl of from 7 to 15 carbon atoms and atoms and R is an alpha-branched alkyl group having from 3 to 4 carbon atoms and a dialkyl phosphonate having the formula:

R O \H wherein R is an alkyl group having from 1 to 4 carbon atoms.

3. Organic material normally susceptible to oxidative deterioration protected by a small antioxidant quantity of the synergistic mixture of claim 2.

' tert-butyl-4-hydroxybenzyl)amine and a dialkyl phosphonate selected from the class consisting of dimethyl phosphonate and d-i-sec-buty-l phosphonate.

6. Organic material normally susceptible to oxidative deterioration protected by a small antioxidant quantity of the synergistic mixture of claim 5.

7. The composition of claim 6 wherein said organic material is lubricating oil.

8. Lubricating o'il containing from about 0.2 to about 1 percent by weight of a 3,S-dialkyl-4-hydroxybenzylamine selected from the class consisting of N,N-dimethyl- N-(3,5-di-tert-butyl-4-hydroxybenzyl)amine and N,N-dimethyl N-(3-methyl-5-tert-butyl-4 hydroxybenzyl)amine and from about 0.025 to about 0.5 percent by Weight of phosphorus as a dialkyl phosphonate selected from the class consisting of dimethyl phosphonate and di-sec-butyl phosphonate.

wherein R is an alkyl group containing from one to 12 carbon atoms, R is an alkyl group containing from 3 to 12 carbon atoms which is branched on the alpha carbon atom, R is selected from the group consisting'of alkyl of from one to 12 carbon atoms, cycloalkyl of from 5 to 6 carbon atoms, aralkyl of from 7 to 11 carbon atoms, aryl of from 6 to carbon atoms, alkaryl of from 7 to carbon atoms, and

no-Q-omwherein R and R are alkyl groups of from 1 to 12 carbon atoms, and X, X and X" are oxygen, said composition containing from about 0.005 to 1,000 parts of said hy-' droxybenzyl amine per part of said dialkyl phosphonate.

13. The composition of claim 12 wherein said hydroxy- .benzyl amine is N,N-dimethyl-N-(3,5-di-tert-butyl-4 hydroxybenzyl) amine.

. 14. The composition of claim 13 wherein said phos- J phonatejs dimethylphosphonate. v

15. The composition of claim 13 wherein said phosphonate 'is di-sec-butyl phosphonate. V

16. The composition of claim 12 whereinsaid hydroxybenzyl amine is N,N-dimethyl-N-(3-methyl-5-tert-butyl-4- hydroxybenzyl) amine. v

17. The composition of claim 16 wherein said phosphonate is dimethyl phosphonate.

18. The composition of claim 16 wherein said phospho'nate is dis-sec-but'yl phosphonate.

19. The composition of claim 11 wherein said lubricating 'oil is a petroleum hydrocarbon oil, I 20. The composition of claim 19 wherein said hydroxybenzyl amine is N,Ndimethyl-N-(3,5-di-tert-butyl- 4-hydroxybenzyl) amine. H 21. The composition of claim 20 wherein said phosphonate is dimethyl phosphonate.

22. The composition of claim 20 wherein said phosphonate is di-sec-butyl phosphonate.

23. The composition of claim 19 wherein said hyfdroxyben'zyl amine is N,N-'dimethyl-N-(3-methyl-5 tertbutyl-4-hydroxybenz'yl) amine.

24. The'composition of claim 23 wherein said phosphonate is dimethyl phosphonate.

25. The comp osition of claim 23 wherein said phosphonate is di-sec-butyl phosphonate.

26. The composition 'of claim 11 wherein said lubricating oil is a synthetic lubricating oil.

27. Functional fluid normally susceptible to oxidative deterioration, containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

28. Saturated hydrocarbon polymers normally susceptible to oxidative deterioration containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

29. Rubber, normally susceptible to oxidative deterioration, containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

30. Antiknock fluid, normally susceptible to oxidative deterioration containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

31. Gasoline, normally susceptible to oxidative deterioration, containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

32. Non-petro'leum fats and oils normally susceptible to oxidative deterioration containing a small antioxidant quantity of the synergistic antioxidant mixture of claim 12.

References Cited in the file'ofthis "patent UNITED STATES PATENTS 2,101,632 Weinrich Dec. 7, 1937 2,169,185 Shoemaker et a1. Aug. 8, 1939 2,220,851 Schreiber Nov. 5, 1940 2,234,379 Martin Mar. 11, 1941 2,363,134 McCleary Nov. 21, 1944 2,413,353 Hunter Dec. 31, 1946 2,432,095 Frey Dec. 9,1947 2,634,824 Drake et "a1. Apr. 14, 1953 2,802,810 Bill Aug. 13, 19 5 7 2,928,790 Bartleson Mar. 15, 1960 2,962,531 Coffield Nov.'29, 1960 FOREIGN PATENTS 654,968 Great Britain July 4, 1951 UNITED STATES PATENT OFFICE QEERTIFEGATE GE QQRBEQTIQN Patent No. 3 115,466 December 24, 1963 Harold D. Orloff et a1.

0 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, lines 50 to 54, for that portion of the formula reading NO- read HO- column 12 line 70, for "3a980" read 3,980 column 14, line 10, for "axelate" read -'azelate column 19, line 48 for "100" read 1000 I Signed and sealed this 4th day of August 1964 EAL) lest:

EDWARD J, BRENNER Commissioner of Patents RNEST W. SWIDER testing Officer UNITED STATES PATENT OFFICE T; ERTIFICATE OF CORRECTION Patent No. 3. ll5 l66 December 24, 1963 Harold D. Orloff et al.

' It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 lines 50 to 54, for that portion of the formula reading NO- read HO" column 12 line 7O for "33980" read 3,980 column 14 line 1O for "axelate" read azelate column 19, line 48 for 100" read lOOO Signed and sealed this 4th day of August 1964" EAL) test:

RNEST W. SWIDER' EDWARD J. BRENNER testing Officer Commissioner of Patents 

1. ORGANIC MATERIAL NORMALLY SUSCEPTIBLE TO OXIDATIVE DETERIORATION PROTECTED BY A SMALL ANTIOXIDANT QUANTITY OF A MIXTURE OF (A) A 3,5-DIALKYL-4-HYDROXYBENZYL AMINE HAVING THE FORMULA 